Inertia member



E. WILDHABER INERTIA MEMBER Dec. 6, 1960 6 Sheets-Sheet 1 Filed March14, 1955 ill/1x INVENTOR. E W LDHABER fl t forne fi INERTIA MEMBER E.WILDHABER Dec. 6, 1960 Filed March 14, 1955 INVENTOR. WI LDHABER FIG E.WILDHABER INERTIA MEMBER Dec. 6, 1960 6 SheetsSheet 5 Filed March 14,1955 I'IIIII'IIIII/ l/IIIIIIII'IIIIIIIIIIIIIIIIIIIII,

ZOO

\\\\\ II A INVENTOR. E. w LDHABER FIG.I7

At orney 5 FIG. l8

Dec. 6, 1960 E. WILDHABER 2,962,905

' INERTIA MEMBER Filed March 14, 1955 6 Sheets-Sheet 4 FIGZI FIGZZF|G.23

INVENTOR.

E. WI LDHABER BY FIG. 24

E. WILDHABER INERTIA MEMBER Dec. 6, 1960 Filed March 14, 1 955 6Sheets-Sheet 5 INVENTOR. E W LD HABE R fii'f arnzy E. WILDHABER Dec. 6,1960 INERTIA MEMBER 6 Sheets-Sheet 6 Filed March 14, 1955 INVENTOR. E.WILD HABE R Aforn? 2 United States Patent INERTIA MEMBER ErnestWildhaber, 124 Summit Drive, Rochester, N.Y.

Filed Mar. 14, 1955,Ser. No. 494,076

24 Claims. (Cl. 74-50) The present invention relates to a rotary inertiamember for steadying a rotary part under a periodically-repeating,varying load. In another aspect, the invention relates to an inertiamember that is combined with a mass-balancing member, for steadying themotion of a rotary part, and for achieving mass balance in areciprocating part driven by said rotary part.

One object of the present invention is to provide a rotary inertiamember for storing up kinetic energy, and alternately transmittingenergy to and receiving energy back from a rotary part under repeatingvarying load, where the inertia member is so connected to the rotarypart that it has much larger fluctuations in speed than the rotary partitself.

Another object of the invention is to provide a rotary inertia memberthat is connected to a timing train which operates with repeatingvarying motion, so that the change of kinetic energy is supplieddirectly by said inertia member and does not disturb the timing.

Another object of the invention is to provide an improved reciprocatingdevice adapted to operate smoothly at high speed.

Another object of the invention is to provide a reciprocating deviceequipped to achieve mass balance while completely avoiding all of theusual drawbacks of mass balance. Ordinarily the big price to be paid formass balance is increased inertia of the parts, which causes therequired torque to fluctuate still more.

Another object of the present invention is toprovide an inertia memberwhich is disposed adjacent the place where it is needed so that kineticenergy flows from the inertia member upon acceleration of the part towhich the inertia member is connected, and flows back again to theinertia member when the parts are decelerated. In this way, thevariation of the torque supplied from the outside is kept at a minimum.

Another object of the invention is to provide an oscillating devicecontaining an inertia member, so that the torque input fluctuates littleor not at all.

A further object of the invention is to provide an inertia member in arepetitive motion device, especially in a device with a constant speedportion, and to constrain the inertia member in such way that theinertia member provides a substantially constant load in the constantspeed portion of the motion of the device, somewhat like a brake, toavoid backlash.

Another object of the invention is to provide a reliable index mechanismwhich can be operated faster than heretofore possible and with maximumsmoothness.

Another object of the invention is to provide an index mechanism whichcan be operated reliably at high speed by supplying the energy foracceleration by an inertia member adjacent the index mechanism, whichtakes back the energy again at deceleration.

Other objects of the invention will be apparent hereinafter from thespecification and from the recital of the appended claims.

In the drawings:

Fig. l is a fragmentary section of a reciprocating mechanism for acutting tool constructed according to one embodiment of the presentinvention and employing an inertia member;

Fig. 2 is a part section, partially broken away, along the line 22 ofFig. 1 looking in the direction of the arrows with the guides for thereciprocating part removed from the frame;

Fig. 3 is a detail view of the tool holder used in the mechanism andshowing the means for clapping the-tool;

Fig. 4 is a view taken at right angles to the view of Fig. 3 and showingthe clapping cams and their drive gear;

Fig. 5 is a section on the line 5-5 of Fig. 2 looking in the directionof the arrows;

Fig. 6 is an axial section of the roller and gear shown in thebroken-away portion of Fig. 2;

Fig. 7 is a part rear view, part section, showing one form of drive tothe face plate of Fig. 1, the drive shown being a varying ratio drivecapable of producing constant slide velocity in one direction;

Fig. 8 is an axial section through the inertia member of Fig. l andshowing how this inertia member is geared to the face plate that drivesthe tool slide;

Figs. 9 and 10 are diagrams explanatory of the embodiment of theinvention as applied in the embodiment illustrated in Figs. 1 to 8inclusive;

Fig. 11 is a diagram explanatory of an embodiment of the invention wherethe face plate is driven at a uniform speed;

Fig. 12 is a section, similar to Fig. 8, but showing the inertia membergeared to a face plate, which is driven at a uniform speed, asillustrated diagrammatically in Fig. 11;

Fig. 13 is a part elevation, part section illustrating a furtherembodiment of the invention and particularly an application of theinvention to an oscillatory member such as the cradle of a spiral beveland hypoid gear generator, the section being taken along the line 13-13of Fig. 14 looking in the direction of the arrows;

Fig. 14 is a part elevation, part sectional view further illustratingthe cradle of Fig. 13 and its mounting;

Fig. 15 is a view on an enlarged scale of the inertia member used in theembodiment of the invention shown in Figs. 13 and 14, and showing alsopart of the gearing connecting the inertia member with the cradle, theview being taken in the direction of a connecting shaft, and some partsbeing shown in section;

Fig. 16 is a fragmentary section showing the drive pinion of Fig. 15 andits mounting;

Figs. 17 and 18 are diagrams explanatory of the principles of operationof the embodiment of the invention shown in Figs. 13 to 16 inclusive;

Fig. 19 is a part elevation, part sectional view, taken on the line19-19 of Fig. 25 looking in the direction of the arrows and illustratinga further embodiment of the invention, and more particularly anapplication of the invention to a notched-plate type of indexingmechanism;

Figs. 20 to 22 inclusive are fragmentary views further illustrating theoperation of the lock-up pawl of this indexing mechanism;

Fig. 23 is a fragmentary view illustrating for comparison the movementof the locking pawl in the operation of a conventional index mechanism;

Fig. 24 is a diagrammatic view illustrating an application of theimproved indexing device of the present invention;

Fig. 25 is a part side elevation, part axial section of the indexingapparatus shown in Fig. 19;

Fig. 26 is a section on the line 26-26 of Fig. 25 looking in thedirection of the arrows;

Fig. 27 is a part side elevation, part axial section of an indexingmechanism similar to that shown in Fig. 25, but having a different typeof inertia member;

Fig. 28 is a section on the line 2828 of Fig. 27 looking in thedirection of the arrows;

Fig. 29 is a diagram illustrative of the principle of operation of theinertia member of Fig. 27;

Fig. 30 is a part axial section, part side view of another form ofindexing mechanism built according to the present invention where theindexing action is derived from a rotary part similar to that shown inFigs. 19 and 25, but where this part makes several revolutions betweensuccessive indexing operations;

Fig. 31 is an end view of the rotary part of Fig. 30, and of associatedparts, looking from the right in Fig. 30;

Fig. 32 is a diagrammatic axial view taken from the right of Fig. 30 andshowing the change gears for driving the control cam;

Fig. 33 is a section on the line 33-33 of Fig. 30 looking in thedirection of the arrows;

Fig. 34 is a cylindrical section developed to a plane, the section beingalong the cylindrical surface described by the axis of the actuatingroller or pin of the rotary part shown in Fig. 30, as the part rotates,and further showing the stationary guideways controlling the axialmotion of the part;

Fig. 35 is a section on the line 35-35 of Fig. 30 looking in thedirection of the arrows; and

Fig. 36 is a diagram illustrating a modified way of changing the inertiaeffect of the inertia member.

Referring first to the embodiment of the invention illustrated in Figs.1 to 10, 40 denotes a rotary face plate to which is rigidly secured ashaft 41. The face plate and shaft are journaled in spaced anti-frictionbearings -42 and 43. Bearing 42 is a cylindrical roller bearingsupporting the face plate around its periphery; and bearing 43 isapplied to the free end of the shaft 41 and is adapted to take axialthrust loads in both directions as well as radial load.

Mounted on the face plate 40 and adiustable radially of the axis of theface plate is a slide 44 (Fig. 1) which carries a crank pin 45 on whicha sliding block 46 is rotatably mounted. The latter engages a straightslot 47 (Fig. 2) of a slide 48. This slide is made of two parts 48, 48"which are adjustable relative to each other in the direction of theslide motion. The slide may carry a cutting tool or a grinding wheel. InFig. 1 the slide is shown as carrying a gear cutting tool 50 which isadapted to cut a cylindrical gear blank 51.

Rotation of the face plate 40 causes the crank pin to move in a circle49 (Fig. 2) and reciprocates the slide 48 along guide rails 52 which arerigidly secured to the machine frame by screws (not shown) which passthrough holes 54 in the guide rails.

The face plate 40 may be rotated either at constant or at varying speed.In the embodiment illustrated it is driven at a speed varying in such amanner that the velocity of the slide 48 is constant in one direction ofstroke, namely, the downward direction. This is accomplished by avarying ratio drive consisting of a cylindrical pinion 55 and a matingface gear 56 (Figs. 1 and 7). The pinion 55 is rotated at a uniformvelocity by applying uniform motion to the helical gear 57, which isrigid with the pinion 55. The face gear 56 has teeth 58 (Fig. 7)arranged along a closed curve 60 which extends about the gear axis 41',which is also the axis of shaft 41, at a varying distance therefrom. Thevarying ratio pair may be of the character fully described in mycopending application Serial No. 431,733, filed May 24, 1954, now PatentNo. 2,770,973, granted November 20, 1956. A drive of this kind willdrive slide 48 at a constant velocity in one direction, except at theends of the stroke near the reversal; and it will give a quick returnmotion.

The quick return motion increases the inertia loads. They areconsiderable, especially at high speed operation.

They tend to shake the whole device and to produce vibra-.

tion. Mass balance is achieved in the present invention in such way thatit will function exactly at all lengths of stroke without adjustment.

For this purpose, a counter-balancing slide 62 is provided which isdriven from the slide 48 to move in the opposite direction. It is driventhrough non-metallic friction rollers 63 (Figs. 2 and 6) and gears 64coaxial therewith. Each friction roller 63 is mounted on the hub portionof a gear 64 to rotate therewith. Each gear 64 is set in an opening ofone of the guide rails 52 and is rotatably mounted on a pin 65 held in abore extending through the guide rails. Each gear 64 meshes with a pairof racks 66 and 67 which are rigid with the slides 48 and 62,respectively. Motion of the slide 48 turns the gears 64 through theracks 66; and the gears 64 move the slide 62 at the same rate in theopposite direction through the racks 67.

The friction rollers 63 engage plane surfaces provided on the sides ofthe racks and rigid with the racks. These plane surfaces may coincidewith the pitch planes of the racks. In ordinary operation, the drive isthrough the friction rollers, backlash being provided in the gear andracks. The positive drive is for safety.

To obtain perfect mass balance, the counter-balance slide 62 should havethe same mass and weight as the slide 48 when its rate of motion is, asindicated, equal to the rate of motion of the slide 48. Also thestraight line described by their centers of gravity of the two slidesshould be the same on both slides, that is, their centers of gravity maybe displaced from each other only in the direction of slide motion. In aview taken in the direction of slide motion the centers of gravityshould appear as coinciding.

This position of the center of gravity of the slide 62 is accomplishedby making the slide 62 reach over the slide 48, as shown in Fig. 1, andby having its main mass on the sides 68 on the level of the slide 48.Slide 62 is disposed more toward one end of the guide rails 52, that is,toward their upper ends. It engages the same guide rails as the slide 48but from the outside while the slide 48 engages them from the inside.

The unit, comprising the face plate 40, the shaft 41, and the partsattached to them, turns at a varying speed so that a varying unbalancedinertia moment results. Ordinarily this has no ill effects because ofthe relatively small moment of inertia of the unit. If on large machinesit is desired to provide mass balance for this inertia moment, this canreadily be done in accordance with the present invention.

The unit is geared at a constant velocity ratio to a member 70 which isrotatably mounted on a shaft 71 secured to the machine frame 53, andhaving an axis parallel to the axis of the shaft 41. The member 76 thenrotates in the opposite direction as compared with the face plate unit,and has opposite inertia moments. For complete balance of the moments,the tooth ratio between the gear 73 and member 70 should be equal to theproportion of the moments of inertia of the face plate unit and of themember 70. The heavier the member 70 is, and the larger its moment ofinertia, the larger would be the gear reduction. The heavier memberrequires less energy for the same balance, as is readily understood. Ifthe moments of inertia are equal, then the same kinetic energy is storedup and released in the member 70 and the face plate unit.

Where the face plate unit is rotated at a uniform velocity to produce aharmonically varying slide velocity there is no need for a member 70.

Mass balance, important as it is for high speed operation, can have itsdrawbacks too. It increases the energy fluctuations and the torquefluctuations.

At the stroke ends the motion of slide 48 is zero so that the kineticenergy of the slide is zero. At midstroke, especially during the quickreturn stroke, the

velocity of the slide and its kinetic energy are a maximum. With massbalance the kinetic energy of the counter-balance slide62 is added. Whenthe velocity of slide 62 is equal and opposite to the velocity of thetool slide 48, then with equal mass its kinetic energy is also the sameas the kinetic energy of the tool slide 48. In other Words, in this casethe balancing slide 62 adds one hundred percent to the torque variation.This may result in torsional vibration. It is particularly serious whenthe motion of slide 48 is a timed motion as where the uniform velocityportion of the cutting stroke of slide 48 is timed with the rotation ofthe gear blank 51 to cause the tool to cut helical teeth of a requiredhelix angle on the gear teeth. Errors in timing are reflected in errorsin the helix angle of the gear produced.

Accordingly, if nothing else were done, one evil would merely have beenexchanged for another. With an inertia member built and connected inaccordance with the present invention, however, not only are torsionaldeflections of the drive and of the timing train avoided in ordinaryreciprocation without mass balance, but also the drawbacks of massbalance can be completely avoided. The inertia member stores up kineticenergy; it delivers the stored up energy; and it receives it back whenneeded. It acts directly on the face plate unit with a single mesh. Theenergy flows directly from the inertia member to the slides and from theslides to the inertia member, without going through a long and yieldingtiming train. It makes high speed operation with mass balance practical.

Reciprocating device with inertia member A principal use of the inertiamember of the present invention is to balance the variations of thekinetic energy.

Figs. 1 and 8 show how an inertia member 74 may be geared to the faceplate 40 for this purpose. Mass member 74 is rigidly secured to a pinion76 by involute splines 77 provided on the pinion member and by a nut 78that threads onto the pinion member. The splines 77 are obtained byturning down or grinding down one end of the pinion teeth so that theyhave a smaller depth. Matching projections or internal teeth areprovided in the hub of the mass member 74. Pinion 76 meshes with a facegear 75 at a varying velocity ratio. Face gear 75 is integral with aplate 79 that, in turn, is rigidly secured to the shaft 41. The pinion76 with the mass member 74 is rotatably journaled in two bearings 80 and81 in a flanged stationary part 82 secured to the machine frame.

The face gear 75 differs from the face gear 56 so that pinion 76 andmass member 74 turn at a varying speed. Just how the speed should varywill be described hereinafter.

The mass member 74 is intended for the slides 48 and 62. Once its motionhas been correctly determined and provided, it will furnish and receivethe varying kinetic energy of the slides 48 and 62 so that the kineticenergy flows back and forth, but remains constant for the unit includingthe slides and the mass member.

At a given stroke length an inertia member determined to exactly balancethe varying inertia torque during the entire cycle of motion keeps thisexact balance at all speeds. While the fluctuations of the kineticenergy of the slides 48, 62 increase with increasing number of turns perminute of the face plate 40 in proportion to the square of that number,the counterpart fluctuations of the kinetic energy of the mass memberincrease in the same way in proportion to the square of that number. Inother words, the balance is not tied down to a given angular velocity.

When, however, the length of stroke is changed, the fluctuationsincrease on the slide; and it becomes desirable to make a change also inthe mass member. In accordance with the present invention this may bedone by changing the mass. The mass member comprises 6 discs 83 (Fig. 8)splined to its body portion 74, and secured against a shoulder thereonby nuts 84 that thread on screws 84'. To increase the energyfluctuations of the mass member, discs 83 are added; and to reduce theseenergy fluctuations, some of the discs 83 are removed. The inertiamoment of a mass member providing exact balance at a given length ofstroke should be doubled when the length of stroke is doubled, tripledwhen the length of stroke is tripled, halved when the length of strokeis halved, etc.

In the diagrams, Figs. 9 to 11, the abscissa represents the turningangle of the uniformly rotating drive pinion 55 (Figs. 1 and 7), acomplete turn of the face plate 49 being plotted. The middle correspondsto the middle position of the working stroke, its ends to the middlepositions of the return stroke. Full line 85 represents the velocity ofthe slide 48 at a given setting of the crank pin 45. Thus the ordinate86 at a point 87 describes the slide velocity at the turning angle ofthe drive pinion 55 corresponding to the point 87.

With the described construction the slide velocity is constant duringthe working stroke; and there is a quick return. The quick return ischaracterized by a large downward ordinate.

The dotted line 88 represents the acceleration or rate of change of thevelocity. The dot and dash line 96 represents the kinetic energy of theslides at the various turning angles. The kinetic energy is proportionalto the square of the velocity, which is always positive. Hence, thecomposite line 90 extends entirely above the abscissa axis 72 andtouches it only, at the points of zero velocity.

The diagram of Fig. 10 refers to the motion of the face plate 40 and ofthe parts rigid with it. The full line curve 89 defines the angularvelocity of the face plate at a given constant turning velocity of thedrive pinion 55. It is a minimum at the middle of the working stroke,and is largest at and near the middle of the return stroke. Thus, theordinate 91 of point 92 defines the angular velocity at the turningposition corresponding to the abscissa of point 92. The dash-and-dotcurve 93 represents the kinetic energy of the face plate, the partsrigid with it, and the members geared to it at a uniform velocity ratio.Member 70 (Fig. l) is such a member. The ordinates of curve 93 areproportional to the square of the angular velocity of the face plate 40.Thus, the ordinate at point 94, corresponding to point 92, isproportional to the square of the velocity expressed by the ordinate ofpoint 92. Curve 93 has its minimum ordinate in the middle of the workingstroke, and its maximum ordinate at the middle of the return stroke. Itis generally similar to the curve 90 of Fig. 9.

The inertia etfects of the rotary bodies, as illustrated in Fig. 10,however, are independent of the length of stroke. For perfect balance onlarge machines two different inertia members should be provided. One ofthese, 74, is adjustable for mass, as described. The other in ertiamember takes care of the rotary body and has a fixed mass. This othermember (not shown) is rigid with a pinion 95 (Figs. 1 and 8) whichmeshes with face gear 96 (Fig. 1) provided on the opposite side of plate79.

Because of the similarity of curves 90 and 93 (Figs. 9 and 10) a singleinertia member will do well in most cases, an adjustable member likemember 74. Its moment of inertia, and its varying ratio gearing are thencomputed to include the effects of the slides 48, 62 and of the partswhich rotate with faceplate 40.

Computation of the mass member and its gearing may be made for a meanlength of stroke after the total change in kinetic energy at a givennumber of cycles per minute has been determined. This change is a givenconvenient percentage of the minimum kinetic energy of the mass member,for instance, thirty percent. For any given angular velocity of the massmember at its position of minimum kinetic energy, the correspondingmoment of inertia can be computed from the given minimum kinetic energy,as well known. Conversely, after assuming a suitable moment of inertiaof the mass member, its angular velocity can readily be computed, firstfor the position of minimum kinetic energy. This postion corresponds tothe middle of the return stroke, where the kinetic energy of the slidesand rotary parts is at its maximum.

As the kinetic energy of the slides and rotary parts changes, it shouldchange on the mass member by the same amount, but in opposite direction,so that the total kinetic energy of the moving parts, including the massmember and the parts attached to it, remains constant. Accordingly, thekinetic energy required on the inertia member is already known for allturning positions of the face plate, and its varying angular velocitycan readily be computed. The operative connection between the massmember and the face plate should be such that this varying angularvelocity is actually realized.

The face gear 75 has its teeth 97 arranged along a closed curve 98 (Fig.8) which extends around the gear axis 41' at a varying distancetherefrom. This curve lies in a plane which is intermediate the planetop surface of the gear teeth and their plane root surface, and which isperpendicular to the gear axis 41'. It can be considered the pitch planeof the gear. A cylindrical pitch surface of the pinion contacts thispitch plane along a straight line. While the instantaneous raito betweenthe pinion and face gear changes, there is always a point on said linewhose distances from the gear and pinion axes are in the proportionequal to said instantaneous ratio. At this point, the pitch point, thegear and pinion have the same velocity in the considered instant, andtrue rolling takes place.

As the gear and pinion turn, this point, the pitch point, moves alongsaid straight line, and describes curve 98 on the pitch plane of thegear. If this curve 98, the pitch line of gear 75, were the same as thepitch line 60 of the face gear 56 (Fig. 7), then pinion 76 would turn atuniform velocity, as does drive pinion 55. Pitch line 98 should,therefore, have a different shape from the pitch line 60 (Fig. 7) ofgear 56.

Let us first compare pitch lines 98 and 60 having the same maximumdistance from the gear axis 41', and having pinions 55 and 76 meshingtherewith which have either equal, or unequal, diameters. Then eachpoint 109 of pitch curve 60 has a corresponding point 108 on pitch curve98 along the same line 10941' radial of the common axis 41' of the twogears. Point 108 can be determined from the known angular velocity ofthe mass member in the considered turning position of the face plate. Itcan readily be demonstrated that the proportion of the radii 41108 and41109 is equal to the proportion of the instantaneous angular velocityof the mass member to its maximum angular velocity. The lattercorresponds to the pitch point of maximum distance from the gear axis41'. Since the instantaneous angular velocity required on the massmember is known, the whole pitch curve 98 can readily be determined inthe described way from the given pitch curve 60.

This curve 98 also determines the motion transmitted between pinion 76and gear 75. Their velocity ratio is the proportion between radialdistance 41-1tl8 to the pitch radius of the pinion 76 when a pitch point108 is in contact with the pitch surface of the pinion. A similarproportion applies to all other pitch points, the proportion of itsradial distance from axis 41 to the pitch radius of the pinion. Thevarying motion gearing can be made in concentional manner, or in themanner described in my pending application Serial No. 431,733 abovementioned.

Uniformly rotating face plate Inertia members may also be used toadvantage when the face plate turns at a different varying rate, or at auniform rate.

The diagram in Fig. 11 relates to a uniformly rotating face plate, andis otherwise similar to the diagram of Fig. 9. A full turn of the faceplate 40 is shown with the abscissa denoting the turning angle. Theordinates of full line represent the velocity of the slide 48 at a giventurning velocity of the face plate. Dotted line 118, composed of shortdashes, describes the acceleration. The dash-and-dot line represents thekinetic energy. All three of these curves are sine curves. The curves115 and 118 repeat once per turn of the face plate. Curve 120 repeatstwice, having two high spots, and two low spots. Accordingly, the gear121 (Fig. 12), which, in this embodiment of the invention, connects theface plate 40 with the inertia member 122, has a generally ellipticalshape. Its teeth 123 are arranged along a pitch curve 124 which has twohigh spots and two low spots. Its exact shape can be determined with thedescribed procedure.

Mass member 122 is rigidly secured to a pinion 126, that is rotatablyjournaled in a flanged member 127, which is secured to the machine frame130. Pinion 126 meshes with face gear 121. The mass member 122 isconstructed like the mass members already described. It has discs 131secured to it. As in the previously described embodiments of theinvention, other discs 131 may be added to increase the inertia momentof the mass member 122.

Further design features of the reciprocation device The gear cuttingtool 50 (Figs. 1 and 3), which may be a rack-type tool, is rigidlysecured to a holder 132 adapted to swing about a pivot 133 that ismounted in part 48" of slide 48. This part also engages guide rails 52,and is rigidly connected with part 48' of the slide through the part 135also hinged on pivot 133. It has a rack toothed portion 134 on its underside which engages rack teeth 136 provided on slide part 48; and it isheld in engagement therewith by screws 137 which engage conventionalT-slots (not shown) provided in slide part 48'.

To change the distance of slide part 48" from slide part 48', the slidepart 48 is first locked vertically on the machine frame in a convenientposition, where the counter-balance slide 62 has moved up enough thatthe screws 137 are accessible. The nuts of the screws are then loosenedand part 135 is moved about pivot 133 to disengage its teeth 134 fromthe rack teeth 136. The machine drive is then operated briefly to movethe slide part 48' the required distance from slide 48". Thereafter thepart 135 is reconnected with the slide part 48', its teeth 134 havingbeen shifted on the rack 136. After such adjustment the slide part 48"is again unlocked from the machine frame, and the slide 48 is ready tooperate.

The tool holder 132 is shown in full lines in Fig. 1 in Withdrawn,clapped position. The cutting position of the tool is indicated indotted lines at 50'. The displacement of the tool and holder 132 to andfrom cutting position, the clapping, is eifected by a pair of cams 140(Figs. 3 and 4) which act on rollers 141, 142 mounted on the tool holder132, and which together with said rollers constitute the clapping means.In this way positive movement of the tool between working and clappedpositions is attained.

Cams 140 are secured to a transverse shaft 143, to which is also secureda hypoid gear 144, so that the cams and this gear are one rigid unit.Shaft 143 is rotatably mounted on a pnojection 145 of the slide part48". Also mounted thereon is a hypoid pinion 146 which meshes with gear144. The axis of pinion 146 is parallel to the direction of the slidemotion. It is driven from a splined shaft 148 which is axially fixed.The pinion slides lengthwise on this shaft during reciprocation of theslide 48. Shaft 148 is coaxial with helical gear 57 and drive pinion 55,and rigid therewith. It is rotatably mounted in the bearings 150, 151,and 152.

If desired, mass balance to a large extent may be provided for theclapping motion by a part 153 shown in dotted lines (Fig. l) and hingedto pivot 133. Part 153 is constrained to move opposite to the toolholder 132. It moves in when the tool holder moves out, and Vice versa.Also, in determining the motion of the mass member '74, or one of themass members, the energy fluctuations in the clapping parts may beconsidered.

As described, the inertia member makes up for the torque fluctuationsdue to the kinetic energy of the parts. It may, however, also be usedfor other purposes. For instance, it may also be used, if desired, tobalance the total supplied torque, and to store up kinetic energy duringthe return stroke to be delivered during the working stroke. The varyingmotion required for this purpose on the inertia member can be determinedwith the above disclosure and the known procedures of the art.

Oscillating device with inertia member Figs. 13 to 18 inclusiveillustrate an application of my inertia member to an oscillating device,and particularly to a machine for grinding or cutting spiral bevel andhypoid pinions in a generating operation. Machines of this kind have anoscillatory cradle 200 rotatably mounted in a machine frame 201. Duringcutting or grinding the cradle is moved at a uniform rate in time withuniform rotation of the pinion to be produced. The amount of motionvaries with different jobs and should be adjustable. On the cradle thereis mounted a face-type grinding wheel or cutter 202. The tool may bedriven from a motor 203 mounted on the cradle, through a belt 204.

As described in my pending application above mentioned, the motion ofthe cradle may be obtained through a varying ratio drive consisting of auniformly rotating pinion 205 meshing with a face gear 206. The gearpair 205, 206 is of the same character as the gear pair 55, 56illustrated in Fig. 7, and may be identical therewith. A face plate 207is rigid with the gear 206. The face plate has a slide 210 radiallyadjustable thereon which carries a crank pin and a roller 208. Theroller 208 engages one side of a slot 211 in a slide 212 which ismounted to move in a direction tangential to the cradle 200. An elasticroller 213 engages the roller 208 and the opposite side of slot 211, andserves to take out all backlash, as described in my application abovementioned. Through the radial adjustment of the roller 208 on the faceplate the slide 212 can be made to travel uniformly through any desireddistance within design limits.

A rack 215 with helical teeth 216 is formed integral with the slide 212,or is rigidly secured thereto. It meshes with a helically-toothedsegment 217 that is secured to the cradle 200, and that is angularlyadjustable thereon. A roller 218 is eccentrically mounted in an arm 220that is pivoted on an axis 221 eccentric of the axis of the roller 218.A weight 222 mounted on arm 220 keeps the roller 218 pressed against therack 215, and maintains the rack in engagement With its segment 217Without backlash.

To take up the end thrust of the inclined teeth of the segment and rackdirectly, a part 224 (Fig. 14) with a groove 225 is rigidly secured tothe rack 215, or is integral therewith. This groove 225 extends in thedirection of the rack motion and has plane sides preferably inclined ata small angle to each other, such as five degrees or ten degrees. Thesides of the groove are engaged by the conical side surfaces of anarcuate part 226 which is rigidly secured to the segment 217 and whichis thereby rigidly secured to the cradle. This arcuate part extendsalong the segment to the ends of the segment. The profiles of thisprojection match the profiles of the groove 225, and directly secure thesegment 217 to the rack 215 in the direction of the cradle axis andsegment axis. In

other words, the axial thrust of the teeth of segment 217 and rack 215is taken up directly by this engagement.

As the cradle is oscillated at a uniform rate during the working stroke,and has a quick return motion, substantial amounts of kinetic energy areperiodically stored up and again released in the moving parts,especially in the cradle when operating at high speed. It is, therefore,important to be able to supply the kineticenergy directly from aninertia member close by, and to absorb it again there and to store itup. This applies especially when the cradle motion is timed with thework rotation, as in the instance referred to.

For this purpose, an inertia member 230 (Figs. 13 and i5), adjustablefor mass and weight, is geared to the face plate 207 by means of acylindrical pinion. 231 and a face gear 232. The face gear has a curvedpitch line 233 which extends around the gear axis 234 at a varyingdistance therefrom. The pitch curve 233 contains all the points wheretrue rolling takes place between the pinion 231 and the gear 232 whenthese points pass the line of contact between the pitch plane of thegear and the cylindrical pitch surface of the pinion.

Pitch curve 233 differs from the pitch curve 235 of the gear 2136, whichmeshes with drive pinion 205. Pitch curve 235 is shown superimposed onpitch curve 233 in Fig. 15 for comparison.

Face gear 232 is integral with a plate 239' that is rigidly secured tothe upper end of a shaft 235 which, in turn, is rigidly secured to theface plate 207 and face gear 206. The shaft 236 is journaled at itsupper end -by means of a bearing 237, and face plate 207 is journaled inthe frame 2111 of the machine by a bearing 238.

The weight and inertia moment required on the mass member 230 isinversely proportional to the square of its angular velocity, and,therefore, decreases rapidly with increasing angular velocity of themass member. Acoordingly, it is advantageous to use as large a speed-upas practically feasible. in the embodiment illustrated in Figs. 15 and16 a helical pinion 231 of small diameter is provided, a diameter sosmall that the pinion would deflect too much under load if it weremerely journaled by two bearings placed at its ends. To avoid unduedeflection, the pinion is journaled on long, cylindrical rollers 240(Fig. 16) which bear against the outside cylindrical surface 241 of thetops of the teeth of the pinion, and which are rotatably mounted incylindrical recesses provided in a stationary part 242. The pinion 231is further journaled in a bearing 243 (Fig. 15) capable of taking upradial load as well as axial thrust load. in both directions.

In the diagrams of Figs. 17 and 18 a complete turn of face plate 207 isconsidered, the corresponding turning angle of the uniformly rotatingdrive pinion 205 being plotted in horizontal direction as the abscissa.The middle position corresponds to the middle of the working stroke; theend positions correspond to the middle of the quick return stroke.

Composite line 243 (Fig. 17) is a velocity diagram of the cradle, theordinates representing the velocity. Curve 244 (Fig. 18) represents thekinetic energy of the cradle and the associated parts, including theslide 212 and face plate 207. It can be determined from the knownvelocities in the per minute.

After the diameter of the pinion 231 has been chosen, its angularvelocity at the middle of the working stroke can be determined. This isthe position of nearly maximum kinetic energy on the inertia member andof nearly minimum kinetic energy on the cradle and associated parts. Theminimum kinetic energy of the inertia member differs from the nearlymaximum kinetic energy by the amount given by the curve 244, at the endsof the curve, that is, at the middle of the return stroke.

The inertia moment and kinetic energy of the inertia member, and henceits angular velocity, can now be devarious turning positions of the faceplate and of the drive pinion 205 at a given number of turnstermined inthe way already described. Curve 245 represents the varying velocity ofthe inertia member as computed from its kinetic energy. Here, however,the horizontal axis 246 corresponds to a definite velocity rather thanZero; and the ordinate upward from axis 246 represents a decrease invelocity. The velocity of the inertia member is a minimum at the ends ofthe diagram where the ordinates are largest. It is at a minimum at themiddle of the return stroke.

The known instantaneous velocity of the inertia member makes it possibleto determine the pitch curve 233 of face gear 232 in comparison with thepitch curve 235 of face gear 206. This determination is indicated inFig. 15 for a face gear 232 of the same diameter as face gear 206, wherethe pitch curves 233 and 235 intersect at a point 248. The radius 234250of any other point of the pitch curve 233 is in the same proportionteradius 234-251 of known pitch curve 235, as the velocity of the inertialmember in the considered position is to its velocity in the positioncorresponding to point 248. This is at a turning angle 248-234251 of theface plate from the last-named position.

The procedure is the same as described with reference to Fig. 8. Herealso the size of the drive can be changed if the same proportions arekept.

Figs. 15, 17 and 18 also illustrate a further advantage which can begained from use of an inertia member constructed according to thepresent invention. In conventional practice a cradle brake is providedon grinders of the type illustrated in Figs. 13 and 14. Its purpose isto provide a steady resistance load so that the same sides of the teethof the gears in the timing train remain in contact during the grindingpass, and backlash has no harmful effect on the tooth surface beingground. This conventional procedure consumes energy, and, what is worse,it tends to heat up the cradle and the machine.

With my invention the inertia member can also perform the function ofthe cradle brake, and do so without consuming any appreciable amount ofenergy and without affecting the temperature of the cradle. It is thendesigned to apply a constant load during the grinding pass to the facegear 232. Face gear 232 is rigidly connected with the face plate 207;and backlash between the face plate 207 and the cradle has already beeneliminated, since at the'rack teeth 216 it is taken out by the roller218; and at the slot 211 of slide 212 it is removed by elastic roller213.

To provide a constant torque, an additional constant acceleration shouldbe produced on the mass member during the grinding or cutting operation.A velocity should be added as indicated by curve 255 in Fig. 17. In thisfigure, increasing ordinates denote increasing velocity. Constantacceleration is indicated by a straight line portion 255 of the velocitygraph.

When this varying velocity of the inertia member is added to thevelocity indicated by curve 245 in the direction required, a velocitycurve 256 results (Fig. 18). This curve intersects curve 245 at the endpoint and at the middle point 258 where the additional velocity is zero.Any point 260 of curve 256 can be obtained by plotting the ordinate ofcurve 255 downwardly from the corresponding point 261 of curve 245. Oncethe velocity curve of the inertia member is known, the procedure is thesame as previously described. Indeed, the pitch curve 233 shown in Fig.15 corresponds to curve 256 (Fig. 18).

If desired, a separate adjustable inertia member may be provided toreplace the cradle brake. It could act on teeth provided at the rear232' (Fig. 13) of plate 239.

Indexing device with inertia member A further, and very importantapplication of my inertia member, is to indexing devices such as areused for instance in the gear cutting machines, cutter Sharpeners,turrets for machine tools, and. in other places. It makes possible avery fast and reliable indexing operation, and does so withoutdisturbing the timing.

One form of index, with inertia member, is illustrated in Figs. 19, 25and 26. It is an index of the slow start and stop type, that is, anindex with a gradual speedup. The type illustrated comprises a Genevawheel 305 provided with protrusions or teeth 309 equi-angularly spacedabout its axis 335. It is intermittently rotated by a driving pin orroller 306 mounted on a shaft 310 (Fig. 25).

The shaft 310 is rotatably mounted in bearings 307, 308, and is rotatedat uniform speed by means which include drive gear 311. The latter issplined to shaft 310 and is rigid with it.

The Geneva wheel 305 shown has six ways 312. secured to flange 313 of ashaft 314 by screws 315. shaft is rotatably mounted in bearings 316,317.

For indexing workpieces having tooth numbers different from the numberof ways in the Geneva wheel, the workpieces are mounted on a shaftseparate from the shaft 314 and geared to the shaft 314 by change gears.For highest accuracy an index plate 325 is secured to the shaft on whichthe work is mounted. The axis of this shaft is denoted at 326. A changegear 320 is secured to shaft 314 by a toothed face coupling 321 andscrew 322 (Fig. 25); and this change gear meshes with a change gearsecured to the shaft which carries the index plate 325. In Fig. 19 onlythe pitch circles 323, 324 of a pair of change gears are indicated.

The index plate 325 has as many notches 331 (Fig. 19) as there are teethin the gear to be cut or ground; and the index plate is held stationaryduring cutting or grinding by a lock dog or pawl 330.

In operation, the Geneva wheel 305 is indexed on each turn of shaft 310,and the shaft 314, to which the Geneva wheel is secured, drives theworkshaft or spindle through the change gears, denoted at 323, 324.Assuming clockwise rotation of the shaft 310 in the end view of Fig. 19,the indexing motion is about to start. It starts when the driving pin306 enters a space 312 between two teeth 309 of the Geneva wheel; and itstops when the driving pin leaves this space. In the time while theGeneva wheel stands still the index plate 325 is locked by the pawl ordog 330. This dog or pawl is carried by a lever 328. The lever isrigidly secured to a shaft 332 whose axis is denoted at 333 (Figs. 20 to22 inclusive). Axis 333 is parallel to the axis 326 of the index plateand parallel to the axes 334, 335 of the shafts 310 and 314.

Immediately before the indexing motion starts, the pawl 330 should startto release the index plate. The release and reengagement of the pawl iseffected by a cam 336 (Fig. 25) which is formed integral with gear 311.Part of the profile 337 of the cam 336 is indicated in dotted lines inFig. 19. The cam acts on a roller 338 rotatably mounted on a lever 340which is rigidly secured to the shaft 332. The outward, disengagingmotion of the lever 340 and of pawl 328 starts in the position shown inFig. 19, constrained by the cam profile 337. A spring 341 attached tothe pawl lever 320 urges the pawl 330 and lever 340 inwardly, andmaintains the roller 338 in contact with the cam. If desired, a secondcam may be provided to rotate with cam 336, and to act on a furtherlever also rigid with shaft 332', to attain positive motion in bothdirections.

To permit high speed operation of the index mechanism without shock orvibration, a mass member 342 (Fig. 26) is provided. This mass member isrigidly secured to a cylindrical pinion 343 in the manner alreadydescribed. Its mass is adjustable by taking ot'f or by adding rings 344.The pinion 343, shown here with straight teeth 345, is in mesh withteeth 346 formed on one end face of gear 311. These teeth constitute aface gear 348. In the instance illustrated, the face gear and pinionrotate at uniform speeds in the region where It is The the driving pin306 is clear of the Geneva wheel. During the indexing operation,however, uniform motion of the face gear produces a varying motion ofthe pinion 343. This is achieved by the illustrated arrangement of theteeth 346 of the face gear 348. They are arranged in a circle about thegear axis 334 for the greater part of the circumference, and in thatregion they represent a conventional face gear. In the portion 350,however, which is active during indexing, they are arranged at a varyingdistance from the gear axis 334 so that the drive to the mass member 342is at a varying ratio when that region is in operation.

This drive may be so determined that the kinetic energy of the inertiamember 342 and of the parts partaking in the indexing motion, isconstant. The kinetic energy of the inertia member, therefore, shoulddepend on the varying kinetic energy of said parts, and, therefore, ontheir instantaneous angular velocity. The first st ep, then, is todetermine these velocities. This can be done by applying the knownprinciples of kinematics.

To determine the angular velocity of the Geneva wheel in proportion tothe angular velocity of shaft 310, different positions of the center ofthe driving pin 306 are considered. In a position such as 351 (Fig. 19)the pin center moves in a radial direction 351-335 relative to theGeneva wheel. The normal 351352 to the direction of this path intersectsthe line of centers 334-335 in the instantaneous center 352 of relativemotion. The instantaneous ratio between the angular velocity of theGeneva wheel and of the shaft 310 is then equal to the ratio of thedistances 334352 and 352-335 of instantaneous center 352 from the twoaxes. This determines the instantaneous angular velocity of the Genevawheel from the given and constant angular velocity of shaft 310. Theangular velocities at other turning positions of the driving pin 306 aresimilarly determined so that finally the distribution of the angularvelocity of the Geneva wheel is determined for the entire indexingmotion. Knowing the instantaneous velocity, we can readily compute theinstantaneous kinetic energy of the indexed parts at a given angularvelocity of shaft 310 and a given ratio of the pitch circles 323, 324.The moment of inertia of the parts is, of course, also known and used.

A curve may be plotted, which gives the varying kinetic energy of theindexed parts in terms of the turning angle of shaft 310. This curve issimilar in character to curve 244 of Fig. 18, but not in shape.

The kinetic energy of the inertia member should vary like this curve,but in a negative manner, so that the largest kinetic energy given bysuch a curve corresponds to the smallest kinetic energy of the inertiamember. This is as described for the other applications of the inertiamember. Here, however, the conditions are somewhat simpler because theshaft 310 with the driving pin 306 rotates at uniform speed.

After assuming the kinetic energy of the inertia member in one position,its varying kinetic energy during the entire indexing cycle isdetermined by the said curve, and with it its varying angular velocitycan be computed. The varying ratio gearing 343, 348 (Fig. 26) can thusbe determined with the directions given.

If desired, the procedure may be exactly as described with reference toFig. 8 when a pitch circle concentric with the face gear is substitutedfor the pitch curve 60 of Fig. 8.

An inertia member determined for a given speed will give perfect balanceof the kinetic energy at all speeds. However, when the ratio of thepitch circles 323, 324 is changed, that is, the angular pitch of thework to be indexed is changed, or when the inertia moments are changed,a different moment of inertia may be required on the mass member, asreadily understood. Fortunately, the larger gears with more teeth andsmaller angular pitch have also larger moments of inertia, so that somecompensation is effected thereby. Thus, the moments of inertia requiredon the mass member are Within reasonable limits.

The counter-rotating Geneva wheel and index plate, and the parts rigidwith them, provide some degree of dynamic mass balance. Perfect dynamicmass balance exists when the moments of inertia of the two rotary bodiesare proportional to the diameters of the pitch circles 323, 324. It canbe provided, if desired for high speed operation, by adding to themoment of inertia of one of the two bodies, if necessary.

Index plates Because of the high speed operation possible with an indexmechanism built according to the present invention, it is also advisableto improve the index plates and their pawls, so that they stand upwithout wear under continued high speed operation.

The function of index plates is not merely a static one; they also haveto give a slight correcting action; they have to supply a smalldisplacement from a nearly correct position to a final accurate positionat the end of each indexing operation. As a pawl moves into lockingengagement with a slot of the index plate, it ordinarily finds the indexplate slightly ofi position. In the engaging process, the pawl engagesthe sides of the slot of the index plate, moves the index plateslightly, and sets the plate right.

Conventional pawls do not apply this last setting touch in the bestmanner. Fig. 23 shows a conventional pawl 400 entering a slot 401 inindex plate 402-. The slot and the pawl have straight sides 403, 404,respectively, which include a moderate angle with one another. As thepawl moves inwardly about its axis 405, it also tips so that its sides404 no longer fit the directions of the sides 403 of the slot. Shouldthe index plate be turned about its axis 406 into contact with the pawl,contact would be made at a corner, either at the corner 407 of a toothof the index plate or at the corner 408 of the pawl. This is not a goodcontact, since it concentrates the loads at the corners. Moreover, it issliding contact and tends to produce wear, and thereby inaccuracy, ifused long enough.

In actuality, contact may be made in a position of the pawl closer tothe bottom of slot 401. But even there contact is made with a corner 407of a tooth of the plate or a corner 408 of the pawl. Fig. 23 also showshow unevenly the sides 404 of the pawl 400 enter into engagement withthe sides 403 of the slot 44.

In accordance with the present invention a shape is provided on the slotand the pawl such that the separation between the slot and pawl is morenearly equal along the whole length of the mating sides of the slot andpawl; and especially a shape such that in the positions near fullengagement the side of the pawl is still capable of contacting with theadjacent side of the slot. Contact concentrated at a corner is therebyavoided; and the final touch between the pawl and the slot, to give thelast correcting action, is made between sides of the two parts ratherthan with a corner. This spreads out the contact; contact stresses arelow; and wear is prevented or sharply reduced.

To this end curved profiles 410, 411 are provided on the pawl 330 and onthe sides of the slots 331 of the index plate. The outer profile 410 ofthe pawl is convex, its inner profile 411 is concave. The matingprofiles of the slot 331 are concave and convex, respectively.

The profiles may be made circular arcs. When the mating profiles arefully matched and capable of having contact along their entire length infull depth position, they are what may be called basic profiles. Thebasic profile 410 is a circular are centered at 415 (Fig. 19). The basicprofile 411 is a circular are centered at 416. Both centers 415 and 416lie on a connecting line 326-333 of the axes of the index plate and ofthe pawl.

at a time but on a whole surface area. -short areas the grinding wheeltends to load up in plunge When the pawl 330 turns on its axis 333, andthe index plate turns with it to retain contact, the center 415, or 416,of each pair of contact profiles moves in the same direction, that is,in a direction perpendicular to line 326-333. At small displacements thecenters of a pair of contacting profiles do not tend to separate. Thus,the profiles tend to remain in contact with each other on their sides.

Fig. 20 shows how a pawl 330 recedes from its slot 331. Pawl 330 hasbeen rocked about its axis 333 the same amount as the pawl 400 of Fig.23. The centers of the pawl profile have been turned to positions 415',416. The slot profiles are still at 415, 4-16. It is readily seen howmuch better the corresponding pawl and slot profiles remain in alignmentwith each other.

Fig. 21 shows the same position of the pawl as Fig. 20; but the indexplate 325 has been turned on its axis 326 so that contact is made on theside 411 of the pawl. The contact is near perfect, not angular as inFig. 23.

Fig. 22 also shows the same position of the pawl as Figs. 20 and 21; buthere the index plate 325 has been turned on its axis 326 so that contactis made on the side 410 of the pawl. Here, also, the contact is nearperfect.

Instead of using fully matched profiles of exactly the same radius onthe pawl profile and the mating slot profile, some ease-oh may beprovided between them, as is customary also on gear teeth. The convexprofile then has a slightly smaller radius than the mating concaveprofile. Thus, on the side 410, the convex pawl profile may be centeredat 415a (Fig. 19), while the mating concave profile is centered at 415b.The two centers are preferably located on opposite sides of the center415 of the basic profile.

One application of the indexing device of the present invention is in agear generator of the gear shaper type, where the cutting tool is ofgear form. In Fig. 24 such a cutting tool is indicated at 360 inengagement with a gear blank 301. As the cutter reciprocates along itsaxis 303 it also turns very slowly about this axis, while the gear blankturns on its own axis 302 as though the gear being cut were meshing withand rolling on a gear represented by the reciprocating cutter 300. Inthis operation each tooth of the cutter takes a good many cuts before itleaves the cutting Zone.

In such a machine, the speed of cutting, or the thickness of the chips,is limited by the high temperature caused at the cutting face adjacentthe cutting edges. Too high a temperature, and a prolonged hightemperature, are detrimental to the tool, because under these conditionsthe tool will require frequent resharpening and will be used up rapidly.

With a fast enough index, as is made possible by the present invention,the cutter can be indexed one tooth after every stroke. After eachcutting stroke it is disengaged completely from the work and indexedduring the return stroke. Then no high temperatures develop at thecutting face adjacent the cutting edges, and whatever temperaturesdevelop, they are not prolonged. Higher cutting speeds can be usedwithout detriment to the tool, or higher feed rates, or both. There is amarked gain of efiiciency in the gear shaping process in general. Insome cases a feed rate may be used such that the cutter makes a completeturn stepwise per tooth of the gear blank.

Another application of the indexing mechanism of the present inventionis to plunge grinding. A fast index will extend the range of plungegrinding and the quality of the product. In plunge grinding, contactbetween the grinding wheel and the work is not merely along a line Forany but grinding, and to produce a poor finish. With a fast index, thegrinding time can be shortened, and repeated more often, so that lesswheel loading occurs and a better teeth 373, may bestraight.

16 finish is produced. Longer areas can be ground too in this mannerwithout incurring a poor finish, and without burns.

Milling cutters, helical shaper tools, etc. can be sharpened by plungegrinding. Also, toothed couplings and clutches, and especially facecouplings and form gears, can be plunge ground when a fast index isprovided. The use of many fast strokes of short duration has the furtheradvantage that the produced tooth surfaces or cutting faces are alike tothe highest degree. There is very little wheel wear around the workbecause of the short grinding engagement. In gear cutting and geargrinding a fast index permits the work to be indexed after every cuttingpass or grinding pass.

Modified inertia member The present invention is by no means limited tothe form of inertia member heretofore described. Broadly an inertiamember can be constructed according to the present invention which iscapable of periodically changing its kinetic energy while the shaft towhich it is operatively connected continues to rotate uniformly. Thereare many ways to effect this change in kinetic energy. The preferred wayis to change the angular velocity of the inertia member periodically.However, it would also be possible to change its moment of inertiaperiodically, and leave its angular velocity constant. Even where itsangular velocity is varied, the variation can be achieved with otherthan a varying-ratio gear pair.

Fig. 27 shows part of an indexing device similar to the one illustratedin Fig. 25. Here, too, the index motion is operated by a driving pin306. This pin is rigid with shaft 360 that is rotatably mounted inbearings 357, 358. The shaft 360 is driven through gear 361. It hashelical grooves 362. These grooves are adapted to receive balls 363. Thegrooves and the balls 363 serve as a mounting for a cam member 364 sothat the cam member can move axially along the helical grooves 362 withlittle friction. In this axial motion the balls roll inside the hub ofmember 364 from one end disc 365 of the hub to the other 366. They fillthe length of the hub only partly so that they can roll in operation.

The outer sides 367, 368 of the member 364 are cam surfaces adapted toengage a pair of tapered rollers 370, 371 mounted on stationary pins372. As the member 364 is rotated through shaft 360 it is constrained tomove axially by the rollers 37%, 371. Member 364 has helical teeth 373(Fig. 28) on its outside surface. These helical teeth are of a handopposite to the hand of the helical grooves 362. A helical pinion 374-meshes with these teeth near the position of the rollers 370, 371, seealso Fig. 28. Pinion 374 is rotatably mounted in antifriction bearings,of which one is shown in Fig. 27 at 375. Rigidly secured to the pinion374 is a mass member 376 adjustable for mass, that is, having removablerings 378.

The speed of the axial displacement of the member 364 affects therotational speed of the mass member 376 so that it can be made to turnat a varying speed during the indexing motion while the shaft 360 turnsat a constant speed.

Since the rotational speeds required on the mass member 376 are knownfor each turning angle of the shaft 360, and can be determined asdescribed, and since consequently the corresponding turning positions ofthe mass memher are also known, the axial displacement to be produced bythe engagement of the earn 364 with the rollers 37%], 371 can bedetermined with the knowledge of the art.

For maximum eifect helical grooves 362 and helical teeth 373 are used.However, either the grooves, or the Thus, straight grooves extendingalong the axis of shaft 360 could be used instead of helical grooves362.

Fig. 29 is a velocity diagram of a mass member in terms of the turningangle of the shaft which contains 17 the driving pin 306 or 366. Anincrease in angular velocity is plotted upwardly; a decrease downwardlyin this diagram. The heavy horizontal line 380 represents an averageangularvelocity. The vertical line 381 at the left end corresponds tothe start of the index motion, as does the line 381' at the right end,their horizontal distance representing a full turn of the shaft with thedriving pin. Lines 382 and 383 represent the middle and end of theindexing motion, respectively.

The determination of the inertia members, as described thus far, hasbeen based on a velocity distribution as indicated in dotted lines 384.Here the angular velocity dropped from a high value at 381 to a lowvalue at 382; and then rose again to the same high value as at 381,reaching it at 383. Then it remained constant between indexing motions.This is considered the best distribution when the friction is negligibleor nearly so.

It is also possible, however, to consider friction, and to take accountof the fact that some of the energy is used up and is lost in thetransfer of the kinetic energy between the mass member and the indexingparts. The aim is to have minimum torque fluctuation in the drive to theindex.

Considering friction, the inertia member has to give up somewhat morekinetic energy than is received by the indexed parts. As indicated bythe velocity curve 385 shown in full lines, the angular velocity of theinertia member drops from a maximum at 381 to a value at 382 lower thanwith the dotted line 384; and at 383 its angular velocity is not up yetto the maximum value. The angular velocity increases gradually in theperiod between indexing motions, to reach the maximum value again at381. Gearing to produce this or any other velocity distribution can bedetermined and made without further instructions.

Horizontal line 380 represents the average angular velocity which theinertia would have without axial motion of the cam member 364.

Many turns of drive shaft between indexing In the indexing device thusfar described, the drive shaft 310 (Fig. 25), which carries the drivingpin 306, efiects an indexing motion at each of its turns. The embodimentnow to be described with reference to Figs. 30 to 35 inclusive indexesless frequently. Here the shaft 510 with the driving pin 506 performs aplurality of turns between indexing. The number of turns is variable. Itcan be set to any desired number, for instance, the tooth number of agear.

The driving pin 506 of the uniformly rotating shaft 510 is ordinarilyout of reach of the Geneva Wheel 505. For indexing, however, the shaft510 advances axially to the proper depth position to engage in a slot511 of the Geneva wheel. Indexing itself then takes place as previouslydescribed. After indexing, the shaft 510 recedes axially to its idlingposition where its driving pin 506 is clear of the Geneva wheel.

The shaft 510 has an extension 509 rigid therewith which carries apinion 508 and a ball bearing 567 adapted to take axial thrust in bothdirections. The outer race of this ball bearing is secured to agenerally tubular slide 512 which is angularly stationary, and which isurged by a strong spring 513 to the right in Fig. 30. Most of the time acatch 514 (Fig. 33) prevents such displacement, and keeps the slide 512,and with it the shaft 510, in the idling position shown. Any suitableknown catch may be used. The catch shown consists of a diametral bossformed on the rod 515 intermediate the ends of this rod. This boss seatsin a cooperating recess provided on slide 512. Rod also has an integraltubular portion 516 above boss 514, and is axially movable. The catch orboss 514 is kept in engagement with its recess on slide 512 by a spring517 which extends into said tubular portion 516.

In the embodiment illustrated, a cam 518 operates to release the catch514. This cam is geared to shaft 510 at the desired ratio of the numberof turns of shaft 510 per indexing cycle. If, for instance, thirty-sixturns are desired, the ratio between the gears 520, 521, 522 and 508(Fig. 32), is thirty-six to one, so that there are thirtysix turns ofthe shaft 510 to one turn of the cam 518. The cam 518 and the changegear 520 coaxial with it are rigidly secured to a circular slide 524turning on a fixed stud 525. Gears 521 and 522 are mounted on anintermediate shaft whose axis is denoted at 52.3. Circular slide 524 ismounted on a fixed part 531 of the machine. It is secured in anyadjusted position thereon by bolts 532. The use of a circular slidemakes a compact construction possible, in spite of the large diameter ofthe cam 518 and gear 520.

As the cam 518 rotates, its projection 526 (Fig. 33) lifts the rod 515and releases the catch 514. The shaft 516 then moves forward (to theright in Fig. 30) under the urge of the spring 513. In this motion it isguided by a stationary groove 527 (Fig. 31) in part 531. This groove isengaged by the spherical front face 529 of the driving pin 506. Thedriving pin reaches full depth position just prior tothe start of theindexing motion. After completion of the indexing motion, the groove 527forces the driving pin and shaft 51f back axially close to its idlingposition. The catch 514 then snaps back again into locking position asthe long idling run starts.

While a mechanical release for the catch has been described, anysuitable known other kind of release could be used also, as, forinstance, a solenoid.

The drive from the Geneva wheel 50 5 to the index plate may be asillustrated in Fig. 19. The outward or releasing motion of the lever528, which carries the locking pawl (not shown), is effected by a lever540 rigidly secured thereto, and cooperating with a cam 536 formed hereat the front end of the shaft 510. Cam 536 is within reach of lever 540only at and near the full depth, forward position of shaft 510. Anotherlever 553, also rigidly connected with the lever 528, maintains positivelocking of the index plate during the idling period. It leans againstthe end 510 (Figs. 30 and 31) of shaft 510. In the advanced position ofthe shaft 510,. this end is out of reach of the lever 553, and thereforepermits inward motion of the lever. In the idling position, it locks thelever in place.

A pair of coaxial, integral gears 554, 555 are rigidly secured to theshaft 510 as by a bolt passing through a hole 556 of the shaft. Gear 554is a conventional spur gear, adapted to transmit uniform motion. Gear555 is identical with gear 554 on most of its circumference. On theremainder, the portion, which corresponds to indexing and which isone-hundred twenty degrees in extent in the example illustrated, it is avarying ratio gear. The two gears 554 and 555 are adapted] to mesh witha conventional spur pinion 558 (Fig. 35). Spur pinion 558 is formedintegral with a shaft 560 (Fig. 30), which is rotatably mounted inbearings 561, 562. A mass memher 536 is rigidly secured to shaft 560.For convenience the shaft 560 is shown as lying in the plane of the axesof the Geneva wheel 505 and of shaft 510. It may, however, be locatedoutside this plane so that it clears lever 553 (Fig. 31).

Gear 555 and pinion 558 are shown in Fig. 35 in a view along their axes.The pitch curve 563 of the gear 555 is the locus of the points on thegear where true roll-ing takes place between the gear and the pinion558, when the points are on the line of centers. The shown positioncorresponds to the middle of the indexing motion. 564 is the pitch pointin this position. The varying ratio pitch curve portion 565--564566joins the pitch circle 568 of the uniform motion portion at points 565and 566. These correspond to the ends of the indexing motion.

An obvious way of producing gear 555, and particularly its varying ratioportion 565-566, is by generating the pinion with a reciprocating geartype cutter which thereby represents the pinion, and by turning the gearblank and the cutter about their axes at the required changing ratiosdesired between thepinion and the gear. The required shape of the teethis then automatically formed on the gear blank. In the portion adjacentpoint 564 the teeth 570 of the gear 555 have an increased pressureangle. In the uniform motion portion the teeth 570 of the g'earhaveconventional shape.

Uniform motion is applied to the gear 554 by a pinion 571 (Fig. 30)which is made-extra long so that it keeps in mesh when the gear 554moves with shaft 510 to the right for indexing.

Pinion 558 of the mass member 536 is also made extra long; but it has adifierent axial position. As the shaft 510 moves to the right, thepinion 558 moves out of engagement with gear 554, and moves intoengagement with gear 555. In the full depth position, when indexingtakes place, it is wholly engaged with gear 555 only. During indexing,the gear 555 and the pinion 558 represents a varying ratio drive, actinglike those described. After indexing, the shaft 510 moves back to idlingposition again so that pinion 558 meshes again with gear 554 at aconstant ratio. The mass member is, therefore, driven at a uniformvelocity when the driving member 536 of the Geneva mechanism is idling;and it is driven at a varying rate when the driving member isfunctioning through pin 506 to drive the Geneva wheel 505 and effectindexing.

Fig. 36 illustrates a modified way of changing the effect of themassmember. This is done by gearing rather than. by a change of mass.The mass of member 536' secured to shaft 560' is embodied as a gear 572which meshes with a change gear 573 rigidly secured to another massmember 574. The latter is rotatably mounted on slide 575 that isadjustable toward and away from the shaft 560.

Here the inertia moments of the, members 536' and 574 remain unchanged.The inertia effect is changed by substituting another change gear 573. Asmaller gear 573 produces a higher speed on mass member 574 andincreases the inertia effect. A larger gear 573 decreases the inertiaeffect. As gear 573 is changed, the slide 575 is adjusted to set the newgear 573 into full mesh with gear 572.

While I have discussed in detail applications of my inertia member tothe machine tool field, it should be understood that these are onlyexamples, and that the invention is broadly applicable to torqueequalization. In fact, while the invention has been described inconnection with several different embodiments thereof, it will beunderstood that it is capable of further modification, and thisapplication is intended to cover any variations, uses, or adaptations ofthe invention following, in general, the principlesof'the invention andincluding such departures from the present disclosure as come withinknown or customary practice in the art to which the invention pertains,and as may be applied to the essential features hereinbefore set forth,and as fall within the scope of the invention or the limits of theappended claims. 7

Having thus described my invention, what I claim is:

1. In combination, a rotary driving part, means for driving said part ata uniform speed, and an inertia mechanism for steadying said rotarydriving part under a periodically-repeating, varying load, said inertiamechanism comprising a rotary mass member, and means operativelyconnecting said mass member to said rotary driving part, said massmember being connected to the means for driving said rotary driving partonly through said rotary driving part, said connecting meansconstraining said mass member to turn at a predetermined varying speedratio while said rotary driving part rotates at a uniform speed, wherebysaid mass member periodically transmits a portion of its kinetic energyto said rotary driving part and periodically receives it back therefrom.

2. In combination, a rotary driving part which is subject to aperiodically-repeating load, means for driving said rotary driving part,and an inertia mechanism for storing energy to be interchanged with saidrotary driving part, comprising a rotary mass member, and gearing forconnecting said mass member with said rotary driving part to produce apredetermined varying speed ratio between said mass member and saidrotary driving part, said gearing including a pair of varying ratiogears, and said mass member being connected to said driving means onlythrough said rotary driving part.

3. In combination, a rotary driving part, means for driving said part,and an inertia mechanism for storing energy to be interchanged with saidrotary driving part comprising a rotary mass member, and gearing forconstantly connecting said mass member with said rotary driving part toproduce a predetermined varying speed ratio between said mass member andsaid rotary driving part, said gearing including a pair of varying ratiogears consisting. of a cylindrical pinion and a face gear having itsteeth arranged at a varying distance from its axis.

4. In combination, a rotary driving part, means for driving said part,and an inertia mechanism for storing energy to be interchanged with saidrotary driving part under a periodically repeating, varying load,comprising a rotary mass member connected with said driving means onlythrough said rotary driving part, and a single pair of toothedvarying-ratio gears operatively connecting said mass member with saidrotary driving part, said mass member being connected with said drivingmeans only through said rotary driving part.

5. In combination, a rotary part, a rotary mass member, means forrotating said part, and means for connecting said mass member to saidrotary part to transmit a predetermined motion at a varying speedbetween said mass member and said rotary part whereby said mass memberperiodically transmits a portion of its kinetic energy to said rotarypart and periodically receives it back therefrom, said mass member beingconnected to said rotating means only through said rotary part.

6. An inertia member for storing energy to be interchanged with a rotarypart adapted to effect periodicallyrepeating motion on a further partfor steadying the motion of said rotary part, comprising a rotary massmember, toothed uniform motion gearing constantly connecting said massmember with said rotary part, a cam operatively connected with saidrotary part, and an operative connection between said cam and said massmember operable to change the speed ratio of said mass member ascompared with said part.

7. An inertia member for storing energy to be interchanged with a rotarypart adapted to effect periodicallyrepeating, varying motion on afurther part of steadying the motion of said rotary part, comprising arotary mass member, a cam mounted on said rotary part to rotatetherewith and to be axially movable thereon, a stationary abutmentadapted to engage said cam to cause an axial displacement thereof whilein engagement therewith, a helical gear secured to said cam member, andan axiallyfixed helical pinion meshing with said gear and fixedlysecured to said mass member, whereby axial displacement of said camchanges the speed of said mass member.

8. An inertia member for storing energy to be inter-. changed with arotary part adapted to effect periodicallyrepeating motion, comprising arotary mass member having a plurality of discs removably secured theretoand changeable to change the inertia of said mass member, and a pair ofvarying ratio gears for operatively connecting said mass member to saidpart at a predetermined varying speed ratio, said pair of gearsconsisting of a pinion rigid with said mass member, and a gear rigidwith said rotary part.

9. A reciprocating device comprising a rotary crank plate having a crankpin radially adjustable thereon, a slide, means connecting said crankpin to said slide to reciprocate said slide upon rotation of said crankplate,

21 means for rotating said crank plate, a rotary mass member, and a pairof varying ratio gears operatively connecting said mass member and saidcrank plate to effect a predetermined varying speed ratio, said gearsconsisting of a pinion rigid with said mass member and of a gear rigidWith said crank plate.

10. A reciprocating device comprising a rotary crank plate having acrank pin radially adjustable thereon, a slide, means connecting saidcrank pin to said slide to reciprocate said slide upon rotation of saidcrank plate, means for rotating said crank plate, a rotary mass memher,a pair of varying ratio gears operatively connecting said mass memberand said crank plate to effect a predetermined varying speed ratio, saidgears consisting of a pinion rigid with said mass member and of a gearrigid with said crank plate, a counter-balance slide, and means formoving said counter-balance slide in the opposite direction to thefirst-named slide upon movement of said first-named slide in eitherdirection.

11. A reciprocating device comprising a rotary crank plate having acrank pin radially adjustable thereon, a slide having a transverse slottherein, a part rotatably mounted on said crank pin and engaging in saidslot to reciprocate said slide on rotation of said crank plate, acounter-balancing slide, toothed gearing connecting the two slides andconstraining said counter-balancing slide to move oppositely to thefirst-named slide in direct proportion to the motion of said first-namedslide, means for rotating said crank plate, a rotary inertia member, anda pair of varying ratio gears for operatively connecting said inertiamember and said crank plate to efiect a predetermined varying speedratio, said pair of gears con sisting of a pinion rigid with saidinertia member and a gear rigid with said crank plate and provided withmore teeth than said pinion.

12. A reciprocating device comprising a rotary crank plate having acrank pin radially adjustable thereon, a slide having a transverse slottherein, a part rotatably mounted on said crank pin and engaging in saidslot to reciprocate said slide on rotation of said crank plate, acounter-balancing slide, toothed gearing connecting the two slides andconstraining said counter-balancing slide to move oppositely to thefirst-named slide in direct proportion to the motion of said first-namedslide, means for rotating said crank plate in such Way as to attain morenearly uniform slide motion in one direction, at least one rotaryinertia member with adjustable moment of inertia, and a pair of varyingratio gears for operatively connecting said inertia member and saidcrank plate to effect a predetermined varying speed ratio, said pair ofgears consisting of a cylindrical pinion rigid with said inertia memberand a gear rigid with said crank plate and having more teeth than saidpinion.

13. A reciprocating device comprising a rotary crank plate having acrank pin radially adjustable thereon, a slide having a transverse slottherein, a part rotatably mounted on said crank pin and engaging in saidslot to reciprocate said slide on rotation of said crank plate, acounter-balancing slide, toothed gearing connecting the two slides andconstraining said counter-balancing slide to move oppositely to thefirst-named slide in direct proportion to the motion of said first-namedslide, a cylindrical pinion and a mating face gear for imparting varyingmotion to said face plate to attain a uniform velocity of said slideduring movement of said slide in one direction, at least one rotaryinertia member with adjustable mo ment of inertia, and a pair of varyingratio gears for operatively connecting said inertia member and saidcrank plate to effect a predetermined varying speed ratio, said pair ofgears consisting of a cylindrical pinion rigid with said inertia member,and of a face gear rigid with said crankplate.

14. In combination, a rotary crank plate having a crank pin radiallyadjustable thereon, a slide having a transverse straight slot, a partrotatably mounted on said crank 22 ,pin and engaging in said slot toreciprocate said slide on rotation of said crank plate, means forimparting varying rotary motion to said crank plate so that said slideis moved at an approximately uniform rate in one direction, an inertiamember, and a pair of varying ratio gears for operatively connectingsaid inertia member and said crank plate, an oscillatory member, andmeans for oscillating said member in direct proportion to the motion ofsaid slide.

15. In combination, a rotary crank plate having a crank pin radiallyadjustable thereon, a slide having a transverse straight slot, a partrotatably mounted on said crank pin and engaging in said slot toreciprocate said slide on Iotation of said crank plate, means forimparting varying rotary motion to said crank plate so that said slideis moved at an approximately uniform rate in one direction, a rotaryinertia member, a pair of varying ratio gears for operatively connectingsaid inertia member to said crank plate in such way that the inertiamember is accelerated during said approximately uniform motion, anoscillatory member, and means for oscillating said member in directproportion to the motion of said slide.

16. In combination, a rotary crank plate having a crank pin radiallyadjustable thereon, a slide having a transverse straight slot, a partrotatably mounted on said crank pin and engaging in said slot toreciprocate said slide on rotation of said crank plate, means forimparting varying rotary motion to said crank plate so that said slideis moved at an approximately uniform rate in one direction, a rotaryinertia member, and gear means for operatively connecting said inertiamember and said crank plate at a predetermined varying speed ratio insuch way that said inertia member is accelerated during saidapproximately uniform motion.

17. In combination, a rotary part, means for rotating said part, anindex plate, means for transmitting intermittent motion from said partto said index plate in which the index plate is accelerated anddecelerated, and a rotary inertia member connected to said part to slowdown during acceleration of said index plate and to speed up againduring its deceleration as compared with the rotation of said part.

18. In combination, a rotary part, means for rotating said part, anindex plate, means for transmitting intermittent motion from said partto said index plate in which the index plate is accelerated anddecelerated, and a rotary inertia member, and gearing for connectingsaid inertia member and said part, said gearing being adapted to slowdown the inertia member during acceleration of said index plate and tospeed it up again during its deceleration, as compared with the rotationof said part.

19. In combination, a rotary part, means for rotating said part, anindex plate, means for transmitting intermittent motion from said partto said index plate in which the index plate is accelerated anddecelerated, and a rotary inertia member, a pair of varying-ratio gearsconnecting said part and said inertia member, one of said pair of gearsbeing rigid with said part and the other of said pair of gears being acylindrical pinion rigid with said inertia member, said gears beingtimed to slow down the inertia member during acceleration of said indexplate and to speed it up again during its deceleration.

20. In combination, a rotary part, means for rotating said part, anindex plate, means for transmitting intermittent motion from said partto said index plate in which said index plate is accelerated anddecelerated, a rotary inertia member, a pair of gears connecting saidpart and said inertia member and constraining said inertia member torotate at a larger speed of rotation than said part, one member of saidgear pair being rigid with said part and the other member of said gearpair being rigid with said inertia member.

21. In combination, a slide, rotary means for imparting a reciprocatorymovement to said slide at a varying velocity, means for driving saidrotary means, a rotary mass member, and means operatively connectingsaid mass member'to'said rotary meansfor transmitting motion at apredetermined varying velocity ratio interchangeably between said rotarymeans and said mass member.

22. In combination, a slide, means for reciprocating 'said slidecomprising a rotary crank plate, a crank pin radially adjustablethereon, and means for rotating said crank plate, a rotary mass member,and means operatively connecting said mass member to said crank plate totransmit motion. at a predetermined varying velocity ratio 'between saidcrank plate and said mass member, said mass member" being connected tosaid rotating means only through said crank plate.

23. In combination, a rotary driving part, means for rotating said partat an approximately uniform speed, a driven member, means forimpartingpcriodically repeating motion from said part to said member, arotary mass element, an operative connection between said element andsaid partito ch'ange'the kinetic energy of said element periodically atthe period of said repeating motion upon unifo'rmirotation' of saidpart, said mass element being connected to said part so that kineticenergy is periodically transmitted from said element to said part andreceived from sai'd'part, to steady said part, said element beingconnected'to saidrotatingimeans only through said part.

24. In combination, a workpiece, a rotary driving part, means forrotating said part in time with said workpiece, a driven member, meansfor imparting periodically repeating motion from said part to saiddriven member, tool v:me'ans mounted on saidmember for engagement withsaid workpiece, a rotary mass element, an operative connection betweensaid element and said part to produce a predetermined'varying speedratiobetween them so as to change-the kinetic energy of said: elementperiodically at the period ofsaid repeating motion upon uniform rotationofsaid part, said mass element' being connected to said part so-thatkinetic energy is periodically transmitted from said element to saidpart and receivedf'rom said part, to steady said-part.

References'Citedin the file of this patent UNITED STATES PATENTS Re.23,296 Dunn Nov. 28, 1950 1,164,250 Aufiero Dec. 14, 1915 1,466,062Rhodes Aug, 28, 1923 1,471,667" Litot Oct. 23, 1923 1,642,120 MathewsSept. 13, 1927 1,787,724 Fedler Jan. 6, 1931 1,791,386 Sprigg Feb. 3,1931 2,278,983 Fuller Apr. 7', 1942 2,282,071 Marsac et a1. May 5, 1942'2,399,721 Brenkert May 7, 1946 2,464,792. Brenkert Mar. 22, 19492,598,110 Clark May 27, 1952 2,656,731 Wildhaber Oct. 27, 1953 2,662,413Gallagher Dec. 15, 1953 2,699,701 Strotheret all Jan. 18, 1955 2,699,745Ayres Jan. 18, 1955 2,704,941 Holford Mar. 29, 1955 2,764,188 HoifmanSept. 25, 1956 2,770,973 Wildhaber Nov. 20, 1956 2,861,635 Orr Nov. 25,1958

